Wireless sensor networks have been proposed with potential applications, for example, in environmental, surveillance, military, health and security monitoring. Such a network includes a group of sensor nodes, each with one or more sensors, an embedded processor, and a low power receiver/transmitter. Typically, these nodes are linked by a wireless medium to perform distributed sensing tasks.
In one such network, for example, the sensor nodes may form an ad hoc network where communication between two arbitrary nodes may take more than one “hop”, i.e., the message may travel through one or intermediate nodes rather than via a direct transmission. The ad hoc network typically has one or more access point (AP) nodes that have greater energy availability and can transmit data to the world at large through wired, e.g., telephone line, or wireless, e.g., cell phone, communications systems. In contrast, the sensor nodes have a limited available power source, e.g., battery, and in turn, limited transmission power.
Some efforts have been made to conserve energy in wireless sensor networks so as to extend the useful life of the network. One such effort, for example, proposes energy conservation in a wireless sensor by identifying nodes that are equivalent from a routing perspective, i.e., redundant, and then turning off unnecessary nodes. Thus, the energy needed for communications is reduced by optimizing network topography for maximum area coverage.